The problem with just updating the system date is that not everything in your computer runs off of that... not to mention that if you aren't ready for it, and your computer checks something against a site that isn't compliant, you can run up against the wall there.I've been hearing from sources I trust that any problems for the average home users should be negligible. As far as what the bugs are, well, get out of the home and they're too many to count.
A sewage treatment plant was running a 9/9/99 check a few months ago, and during the test, a completely unconnected discharge valve blocked. The systems being tested were registering as everything being fine, but one of the defects was that apparently the valve malfunctioned on September 9th. The security system was checking for defects on the preset check date that doesn't exist. Net result was a couple thousand gallon sewage spill.
That is the kind of thing that people are expecting. Most (if not all) of the REALLY big problems have sooooo many techies sitting on them that even if something did go wrong, it'd be fixed very quickly. The most realistic appraisal I've heard is to expect a certain amount of phone outage (due to the thousands of people flooding online and calling to ensure that the world didn't end), and a small amount of annoyance as regional systems work the bugs out.
M